Biochemical characterization of a lichenase from Penicillium occitanis Pol6 and its potential application in the brewing industry

Biochemical characterization of a lichenase from Penicillium occitanis Pol6 and its potential application in the brewing industry

Abstract

•Lichenase (EGL) secreted by the fungus Penicillium occitanis was purified.•The purified enzyme showed an optimum activity at pH 3.0 and 50–60 °C.•The half-lives of EGL at 60 °C and 70 °C were 80 min and 21 min, respectively.•EGL hydrolyzed lichenan to yield trisaccharide and tetrasaccharide as the main products.•Biochemical proprieties suggest that EGL is a good candidate for brewing industry.

The purification and characterization of an extracellular lichenase from the fungus Penicillium occitanis Pol6 were studied. The strain produced the maximum level of extracellular lichenase (45 ± 5 U ml−1) when grown in a medium containing oat flour (2%, w/v) at 30 °C for 7 days. The purified enzyme EGL showed as a single protein band on SDS–PAGE with a molecular mass of 20 kDa. Its N-terminal sequence of 10 amino acid residues was determined as LDNGAPLLNV. The purified enzyme showed an optimum activity at pH 3.0 and 50–60 °C. The half-lives of EGL at 60 °C and 70 °C were 80 min and 21 min, respectively. Substrate specificity studies revealed that the enzyme is a true β-1,3-1,4-d-glucanase. The enzyme hydrolyzed lichenan to yield trisaccharide, and tetrasaccharide as the main products. Under simulated mashing conditions, addition of EGL (20 U/ml) or a commercial β-glucanase (20 U/ml) reduced the filtration time (25% and 21.3%, respectively) and viscosity (10% and 8.18%, respectively). These characteristics indicate that EGL is a good candidate in the malting and brewing industry.